This invention relates generally to magnetic disk data storage systems, and more particularly to magnetic write transducers and methods for making same, and most specifically to high density magnetic write transducers and methods of making same.
Magnetic disk drives are used to store and retrieve data for digital electronic apparatuses such as computers. In FIGS. 1A and 1B, a magnetic disk data storage systems 10 of the prior art includes a sealed enclosure 12, a disk drive motor 14, a magnetic disk 16, supported for rotation by a drive spindle S1 of motor 14, an actuator 18 and an arm 20 attached to an actuator spindle S2 of actuator 18. A suspension 22 is coupled at one end to the arm 20, and at its other end to a read/write head or transducer 24. The transducer 24 (which will be described in greater detail with reference to FIG. 2A) typically includes an inductive write element with a sensor read element. As the motor 14 rotates the magnetic disk 16, as indicated by the arrow R, an air bearing is formed under the transducer 24 causing it to lift slightly off of the surface of the magnetic disk 16, or, as it is termed in the art, to xe2x80x9cflyxe2x80x9d above the magnetic disk 16. Alternatively, some transducers, known as xe2x80x9ccontact heads,xe2x80x9d ride on the disk surface. Various magnetic xe2x80x9ctracksxe2x80x9d of information can be written to and/or read from the magnetic disk 16 as the actuator 18 causes the transducer 24 to pivot in a short arc as indicated by the arrows P. The design and manufacture of magnetic disk data storage systems is well known to those skilled in the art.
FIG. 2A depicts a magnetic read/write head 24 including a substrate 25 above which a read element 26 and a write element 28 are disposed. Edges of the read element 26 and write element 28 also define an air bearing surface ABS, in a plane 29, which can be aligned to face the surface of the magnetic disk 16 (see FIGS. 1A and 1B). The read element 26 includes a first shield 30, an intermediate layer 32, which functions as a second shield, and a read sensor 34 that is located within a dielectric medium 35 between the first shield 30 and the second shield 32. The most common type of read sensor 34 used in the read/write head 24 is the magnetoresistive (AMR or GMR) sensor which is used to detect magnetic field signals from a magnetic medium through changing resistance in the read sensor.
The write element 28 is typically an inductive write element which includes the intermediate layer 32, which functions as a first pole, and a second pole 38 disposed above the first pole 32. The first pole 32 and the second pole 38 are attached to each other by a backgap portion 40, with these three elements collectively forming a yoke 41. Above and attached to the first pole 32 at a first pole tip portion 43, is a first pole pedestal 42 abutting the ABS. In addition, a second pole pedestal 44 is attached to the second pole 38 at a second pole tip portion 45 and aligned with the first pole pedestal 42. This area including the first and second poles 42 and 44 near the ABS is sometimes referred to as the yoke tip region 46. A write gap 36 is formed between the first and second pole pedestals 42 and 44 in the yoke tip region 46. The write gap 36 is filled with a non-magnetic material. This non-magnetic material can be either integral with (as is shown here) or separate from a first insulation layer 47 that lies below the second pole 38 and extends from the yoke tip region 46 to the backgap portion 40. Also included in write element 28 is a conductive coil 48, formed of multiple winds 49, that is positioned within a dielectric medium 50 that lies above the first insulation layer 47. As is well known to those skilled in the art, these elements operate to magnetically write data on a magnetic medium such as a magnetic disk 16.
More specifically, an inductive write head such as that shown in FIGS. 2A-2C operates by passing a writing current through the conductive coil layer 48. Because of the magnetic properties of the yoke 41, a magnetic flux is induced in the yoke 41 by write currents that are passed through the coil layer 48. The write gap 36 allows the magnetic flux to fringe out from the yoke 41 (thus forming a fringing gap field) and to cross a magnetic recording medium that is placed near the ABS. A critical parameter of a magnetic write element is a trackwidth of the write element, which determines a magnetic write width (MWW), and therefore drives the recording track density. For example, a narrower trackwidth can result in a narrower MWW and a higher magnetic recording density. The trackwidth is affected by geometries in the yoke tip portion 46 (see FIG. 2A) at the ABS. These geometries can be better understood with reference to FIG. 2B, a view taken along line 2Bxe2x80x942B of FIG. 2A.
As can be seen from FIG. 2B, the first and second poles 32, 38 can have different widths W1, W2 respectively in the yoke tip portion 46 (see FIG. 2A). In the shown configuration, the trackwidth of the write element 28 is defined by the width Wp of the second pole pedestal 44. As can be better seen from the plan view of FIG. 2C taken along line 2Cxe2x80x942C of FIG. 2B, the width Wp of the pole pedestals typically is substantially uniform. The gap field of the write element also can be affected by the throat height TH, which is measured from the ABS to the zero throat ZT, as shown in FIG. 2A. Thus, accurate definition of the both trackwidth and throat height is critical during the fabrication of the write element.
However, the control of trackwidth and throat height can be limited with typical fabrication processes, such as masking and plating at the wafer level. For example, the trackwidth sigma "sgr"tw, can be limited to a minimum of 0.07 microns. These problems are further aggravated with increasing topography over which the trackwidth-defining element is formed. Such topography is created by the various heights of other elements that have been formed before the trackwidth-defining element is formed. Greater trackwidth control can be attempted using other processes such as focused ion beam (FIB) milling, however such processes can be expensive. Alternatively, the trackwidth can be defined by the first pole width W1. However, such processes can also be expensive, complex, and result in lower production yields.
It can also be very difficult and expensive to form very small trackwidths using typical processes. Therefore, forming a pole pedestal having a trackwidth of about 1.25 microns can be very difficult and expensive, with smaller trackwidths posing even greater challenges. When demand for higher density writing capabilities drives smaller trackwidths, this aspect of fabrication becomes increasingly problematic.
An additional disadvantage of some current write element configurations, such as those shown in FIGS. 2A-2C, is a secondary pulse phenomenon that can degrade recording performance. Typically, an intended primary pulse is generated to record a single bit of data. However, due to magnetic saturation at the interface between the second pole pedestal 44 and the second pole tip portion 45, an unintended second pulse may be produced just after the primary pulse. As linear density increases, in other words, as one attempts to write bits closer together and primary pulses follow one another more closely, this second pulse effect may distort the waveforms of the primary pulses. Such distortions generated by the prior art write elements shown in FIGS. 2A-2C when operated at high linear densities makes them unsuitable for high density magnetic recording applications.
Accordingly, what is desired is a wire element that is effective for applications having data densities on the order of 40 Gbits/in2 with a trackwidth of less than about 1 micron and exhibiting substantially no secondary pulse phenomenon. Further, it is desired to achieve these qualities inexpensively, easily, and while maximizing throughput.
The present invention provides a magnetic write element and method for making the same that provides high writing performance in high density applications, and can be inexpensively and quickly fabricated with high yield. Specifically, a write element is provided which has a very small trackwidth, good trackwidth and throat height definition control, and substantially no secondary pulse.
In an embodiment of the present invention, a magnetoresistive device for recording data on a magnetic media includes a first pole having a first pole first surface lying substantially in a plane and a second pole having a second pole first surface lying substantially in the plane. Also, the device includes a tapered second pole pedestal disposed between the first pole and the second pole and magnetically connected to the second pole. The tapered second pole pedestal has a second pole pedestal first surface lying substantially in the plane, and has a second pole pedestal width measured substantially parallel to the plane, wherein the second pole pedestal width, of at least a portion of said second pole pedestal that is proximate the plane, increases with increasing distance away from the plane.
In some embodiments of the present invention, the device can further include a first pole pedestal between the first pole and the second pole pedestal and magnetically connected to the first pole. Further, the first pole pedestal can have a first pole pedestal first surface lying substantially in the plane, and hae a first pole pedestal width measured substantially parallel to the plane, wherein the first pole pedestal width, of at least a portion of the first pole pedestal that is proximate the plane, increases with increasing distance away from the plane.
In another embodiment of the present invention, a method of forming a magnetoresistive device includes providing a first pole and forming a first tapered pole pedestal having a first pedestal ABS portion that includes an ABS plane. The first pedestal ABS portion has a first end and a second end, wherein a width of the tapered pole pedestal increases from the first end to the second end. The method also includes forming a write gap layer formed of non-magnetic, electrically insulating material between the first pole and the first tapered pole pedestal. Also, a second pole that is magnetically connected to said first tapered pole pedestal is formed. The method additionally includes exposing a first pedestal ABS surface, of the first tapered pole pedestal, within the ABS plane by lapping the first pedestal ABS portion beginning at the first end, wherein the width of the first tapered pole pedestal at the first pedestal ABS surface is substantially equal to a desired width.
In additional embodiments of the present invention, the method can further include providing a read sensor having a first end and including the ABS plane. When the first pedestal ABS surface is exposed, a sensor ABS surface within said ABS plane is also exposed, thereby defining a stripe height of the read sensor.
By defining the trackwidth in this way, very small trackwidths can be realized, with very accurate control. These improvements can therefore result in greater write performance, including use in high density applications, such as 40 Gbit/in2. Further, these advantages can be realized in the present invention with minimal expense, complexity, and time of manufacture.
These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following descriptions of the invention and a study of the several figures of the drawings.